The invention relates to a method for operating an internal combustion engine, especially of a motor vehicle, wherein fuel is injected into a combustion chamber in a first operating mode during a compression phase and in a second operating mode during an induction phase. In the method, there is a switchover between the operating modes and the internal combustion engine has an exhaust-gas recirculation with an exhaust-gas recirculation valve. The invention likewise relates to a corresponding internal combustion engine as well as a corresponding control apparatus for an engine of this kind.
A method of this kind, an internal combustion engine of this kind and a control apparatus of this kind are all, for example, known from a so-called gasoline direct injection. There, fuel is injected into the combustion chamber of the engine in a homogeneous operation during the induction phase or in a stratified operation during the compression phase. The homogeneous operation is preferably provided for the full-load operation of the engine; whereas, the stratified operation is suitable for idle operation and part-load operation.
In an internal combustion engine of this kind, fault functions can occur. Accordingly, it is, for example, possible that the exhaust-gas recirculation valve jams or can no longer be moved. In this case, it must be ensured that the engine does not go into a critical operating state.
It is an object of the invention to provide a method for operating the internal combustion engine wherein it is ensured that fault functions of the exhaust-gas recirculation do not lead to critical operating states of the engine.
This object is solved in accordance with the invention in a method of the kind mentioned initially herein in that the engine is switched over into the first operating mode when the exhaust-gas recirculation valve jams in the open position. The task of the invention is solved correspondingly in an internal combustion engine and a control apparatus of the kind mentioned initially herein.
If the exhaust-gas recirculation valve jams in the open position, then the engine is switched over into the stratified operation in accordance with the invention. In the stratified operation, the open exhaust-gas recirculation valve can be easily considered in the control (open loop and/or closed loop) of the engine. A critical state can therefore not occur. With the selection of the stratified operation as an emergency operation, a reliable operation of the engine is ensured. The disadvantage that, in stratified operation, only a reduced torque can be generated by the engine is greatly outweighed by the advantage of a reliable operation.
In an advantageous further embodiment of the invention, the engine is switched over into the second operating mode when the exhaust-gas recirculation valve is jammed in the closed state.
If the exhaust-gas recirculation valve jams in the closed state, then the engine is switched over into the homogeneous operation in accordance with the invention. In the homogeneous operation, and for a closed exhaust-gas recirculation valve, the engine can be easily operated and especially without exceeding exhaust-gas limit values. A reliable operation of the engine is thereby provided also in this fault case.
In a further advantageous embodiment of the invention, the exhaust-gas recirculation valve is closed in another fault function of the exhaust-gas recirculation and the engine is switched over into the second operating mode. It is especially advantageous when a jamming of the exhaust-gas recirculation valve is determined with the aid of a sensor.
Of special significance is the realization of the method of the invention in the form of a control element which is provided for a control apparatus of an engine, especially of a motor vehicle. A program is stored on the control element which is capable of being run on a computer, especially on a microprocessor, and is suitable for executing the method according to the invention. In this case, the invention is realized by a program stored on the control element so that this control element, which is provided with the program, defines the invention in the same way as the method which the program can carry out. Especially an electric storage medium can be used as a control element, for example, a read-only-memory or a flash memory.
Further features, application possibilities and advantages of the invention will become apparent from the following description of embodiments of the invention which are illustrated in the drawing. All described or illustrated features define the subject matter of the invention by themselves or in any desired combination independently of their summary in the patent claims or their dependency as well as independently of their formulation or presentation in the description and/or in the drawing.